Curiosity Gets Her Wheels

She’s a rover with places to go and things to do, so one of the main components of NASA’s next Mars rover, the Mars Science Lab (named Curiosity) is wheels. Last week, the wheels and a suspension system were installed on the rover, an important step in getting ready for her mission to Mars. Launch is currently scheduled for sometime between November 25 and Decemeber 18, 2011, and Curiosity’s mission is to study its landing site for habitable environments – both ancient and current.
There are four landing sites on Mars that are still in the running: Eberswalde Crater Delta (24.0°S, 327.0°E), Holden Crater (26.4°S, 325.3°E), Gale Crater ( 4.6°S, 137.2°E) and Mawrth Vallis (24.0°N, 341.0°). Wherever Curiosity goes, she will examine rocks, soil and atmosphere with a diverse payload of tools, including a laser to vaporize patches of rock from a distance and an instrument designed to test for organic compounds. (Watch the video for a demonstration).

Curiosity has six wheels, each of which has its own drive motor, and it uses a rocker-bogie suspension system like the previous Mars rovers, Spirit, Opportunity and Sojourner.

But the landing system is completely different. Curiosity is too large to use an airbag system, so it will used a Sky-Crane, a rocket-powered descent stage that lowers the rover directly onto the Martian surface on a tether.

If Curiosity launches during the currently scheduled launch window, she will land in August 2012.

13 Responses

I’m all for the space program, always have been. But I am getting a bit bored with the Mars obsession. Possibly the least interesting of all the planets — to me at least. Yawn. Well, so be it. Why is this rover so large? Seems like that means it needs more power, so what’s the advantage?

No sign of solar cells, I presume they haven’t been installed yet although the animations don’t show any either. I hope they have come up with some high tech solution for keeping the panels clean and free of dust. You know, like a brush on an arm! 😉

Not sure pahies about the power. Thermoelectric power needs temperature differential and Mars surface environmental temperature may not do the job. Also the radiator surface will get contaminated with dust.

I know I may be asking too much. But this new one still travel at turtles pace. They should call it Mars Turtle Explorer.

Power source
The MSL will be powered by radioisotope thermoelectric generators (RTGs), as used by the successful Mars landers Viking 1 and Viking 2 in 1976. Radioisotope power systems are generators that produce electricity from the natural decay of plutonium-238, which is a non-weapons-grade form of that radioisotope used in power systems for NASA spacecraft. Heat given off by the natural decay of this isotope is converted into electricity, providing constant power during all seasons and through the day and night, and waste heat can be used via pipes to warm systems, freeing electrical power for the operation of the vehicle and instruments.

The MSL power source will use the latest RTG generation built by Boeing, called the “Multi-Mission Radioisotope Thermoelectric Generator” (MMRTG). The MMRTG is a flexible and compact power system under development that is based on conventional RTGs. The MMRTG is designed to produce 125 watts of electrical power at the start of the mission and 100 watts after 14 years. The MSL will generate 2.5 kilowatt hours per day compared to the Mars Exploration Rovers which can generate about 0.6 kilowatt hours per day. Although the primary mission is planned to last about 2 Earth years, the MMRTG will have a minimum lifetime of 14 years.

Before some people start freaking out like little girls at a clown party… Plutonium-238 isotope produces heat through natural decay by giving off ALPHA particles (i.e. helium nuclei). Alpha particles can travel a whopping 3 inches or so through air; even with all this power it cannot manage to find its way through cloting, paper, skin, etc.

Basically, the only way plutonium-238 can harm you, is if you inhale it. In order to minimize this risk, NASA puts it in a ceramic form. This way, if something happens, it is resistant to fire. If it falls, it will break off into pieces which are too large to breathe in. If it splashes into water, it has very low solubiilty. In short, it doesn’t move very easily through the Earth or Martian environment…in ceramic form, it isn’t going to react with any chemicals.

The containers which house the system, have been put through a battery of tests to ensure there would be no danger due to a launch/re-entry problem, motor explosion, etc.
Somewhere, the US Department of Energy has all the specs and test standards it must go through…. please no conspiracy theories. Even the astronauts on the Apollo missions had plutonium-238 strapped near them; not to mention many other NASA missions like Viking, Cassini, New Horizons to name a few.

Emilio…
I’m sure if you designed a motor which could drive all six wheels faster, while carrying the equipment on board, using the available power, NASA will surely use it… not to mention you would likely be very wealthy.

Yet… there are no roads, it isn’t exactly the smoothest terrain, while we have some relief maps, nothing to the tune of < 1M, no gps, and also no direct control… so it has to be able to sense it is going off a cliff and still manage to stop. Just how fast do you think it can safely move? Keep in mind, you can't change wheels, suspension or anything else which breaks because you want to go fast. 🙂

However, I do not entirely agree with the presumed need to look for clays to get to fossils as displayed in the movie. Noachian age equivalent fossils have been found “in pristine condition” in siliclastic deposits on Earth. I.e. sandstones instead of clays may be good enough – or even better!

@ kcuhC:

Why is this rover so large? Seems like that means it needs more power, so what’s the advantage?

Primarily this is a result of NASA strategy “follow the water” being so successful (water found) that the next goal is “follow the organics (with the water)”. Curiosity has a whole suite of experiments for that more complicated task.

Also, since it is a follow up NASA Flagship mission it has been given the resources to go at it for a longer time. Both NASA and, I believe, ESA has cycles with massive low risk flagships and less expensive technological or exploratory high risk missions interleaved.

“The MSL will generate 2.5 kilowatt hours per day compared to the Mars Exploration Rovers which can generate about 0.6 kilowatt hours per day. Although the primary mission is planned to last about 2 Earth years, the MMRTG will have a minimum lifetime of 14 years.”

I’m really liking that! Good job! Now tell me again why we don’t have dozens more Curiosity-like robotic explorer’s being built? For Mars, the moon and NEO rocks….*

Aqua, my previous comment which touches on this (“more Curiosity-like robotic explorer’s”) is still in moderation.

Basically these missions are very expensive. They are so much a bottleneck that NASA (and I believe ESA) has cycles with cheaper missions in between.

Right now there are more reasons to abstain, related to the RTGs themselves:

– There isn’t enough of the required radioisotopes. It is up in the air if Congress will allow any more RTGs; I believe the question has been put before them many times already, because it is stupid to run out of material.

If they pay, it will take ~ 5 years before the new production line is delivering. Meanwhile there is IIRC material for one more great science mission of this type. US is building up to another “gap”.

– There is a technological generation shift. The Apollo era RTGs relied on high temperature ceramics which production hasn’t been supported AFAIU. These MMRTGs are smaller and cheaper but also, I believe, not using “the very best” material any more. If so, another derelict of US unwillingness to keep the Apollo era outstanding products around.

Going to Stirling RTGs, under testing, will AFAIU catch up with the quality gap somewhat.